System of control



A. J. HALL.

SYSTEM OF CONTROL.

APPLICATION nun lmr.

Patented Mar. 15, 1921.v

4 SHEETS-SHEET l.

INVENTOR.

ArfhurJ Halt AITTORNEY" A. J. HALL.

SYSTEM OF CONTROL- APPLICATION FILED MAR.13, I916- 1,37 1, 558, Patented Mar. 15, 1921.

4 SHEETSSHEET 2- WITNESSES 4 INVENTOR ArfhurJ Hall. BY

TTORNEY A. J. HALL.

SYSTEM OF CONTROL.

APPLICATION FILED MAR.13, me.

1,371,558. Patented Mar. 15,1921..

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' WITNESSES: INVENTOR A. J. HALL.

SYSTEM OF CONTROL.

APPLICAHON nun MAR. 13. 1916.

1,371,558. Patented Mar. 15,1921.

4 SHEETS SHEET 4.

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Hi i i l c/ WITNESSES: INVENTOR WW ATTORNEY ARTHUR ."r. HALL, or WILKINSBURG,

PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

SYSTEM OF CONTROL.

Application filed March 13, 1916. Serial No.

To all whom it may concern:

Be it known that I, ARTHUR J. HALL, a subject of the King of Great Britain, and a resident of Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Systems of Control, of which the following is a specification.

My invention relates to systems of control for dynamo-electric machines-and especially to the control of electric railway motors and the like during regenerative periods.

The object of my invention is to pro vide, in a system of the above-indicated character, certain novel main-circuit connections and auxiliary-circuit interlocking arrangements whereby a relatively simple, reliable and economical control system obtains.

My invention may best be understood by reference to the accompanying drawings wherein Figure 1 is a diagrammatic view of the main circuits of a system of control embodying my invention; Fig. 2 is a diagrammatic view of the auxiliary governing cir cuits for manipulating the various circuit switches that are illustrated in Fig. 1; Fig. 3 and Fig. 4; are sequence charts of weltknown form for indicating the desired order of operation of the various switches during the accelerating and regenerative periods, respectively; Fig. 5 is a detailed diagrammatic view of one of the complete main-circuit switches that are shown in Fig. l; and Fig. 6 to Fig. 9, inclusive, are simplified diagrammatic views corresponding to different operating connections, as indicated by the accompanying legends.

Referring to Fig. 1, the system shown comprises a plurality of suitable supply-circuit conductors respectively marked Trolley and Ground; a plurality of dynamo-electric machines respectively having armatures A1, A2, A3 and A l and sub-divided field-magnet windings F1, F2, F3 and F4; of the series type; a reversing switch RS, here shown conventionally, but preferably of a familiar electrically-controlled type as indicated in the auxiliary circuits of Fig. 2, for reversing the electrical relations of the several main armatures and field windings; a main circuit resistor ARI with which is associated a plurality of suitable short-circuiting switches R1, R2, R3 and Re; a second main-circuit resistor AR2 with which is similarly associated a plurality of switches RR-l, BB2, BB3

Specification of Letters Patent.

Patented Mar. 15, 1921. 83,732.

and RRt; a third main-circuit resistor JR that is adapted to be short-circuited bya switch J 3; a plurality of motor-controlling switches LS1, LS2, LS3, J1, J2, M1, M2, G1 and G2; a plurality of suitable motor-cutout switches C12 and C34 that are respectively associated with the pairs of armatures Al and A2, and A3 and A4, for the customary purposes of excluding the one or the other set of motors from circuit in case of injury thereto; a plurality of switches l and 2, and 3 and 4: that are respectively associated with the pairs of main field windings F1 and F2, F3 and F 4 for eflecting the well-known field-control connections; a limit switch L of a familiar type; a changeover switch CO preferably of the drum type and elec trically controlled, as explained in connection with Fig. 2, for arranging certain of the main-motor, and also of the auxiliary, circuits during both the accelerating and regenerative periods, in accordance with its occupation of the positions marked Acc. and Reg; a field-circuit-controlling device PK of the drum type having an operating mechanism OM, for varying the active value of a plurality of resistors FBI and F112 that are disposed in circuit with the main field windings during the regenerative period, as set forth later, a motor-generator or dynamotor D of a familiar type for supplying exciting energy to the main-field-winding circuits during the regenerative period; and a relay device RD, which is associated with the main and the auxiliary circuits in a manner to be described.

The motors are here shown as being operated in pairs of permanently-connected armatures and field windings, and groups of switches are supplied in several cases to provide a series or" breaks, whereby, the particular system to be described is adapted for relatively high-voltage operation such as 1500 volts direct current. However, it will be understood that the novel features of my invention are applicable to various other control systems and the number and arrangement of motors, in general, is immaterial to the present invention.

The 'dynamotor D is shown as comprising a driving or motor armature M that is connected through a suitable field winding DF across the supply circuit. and a generator or exciting armature winding G that is preferably disposed upon the same shait,-S as the motor armature. However, it will be appreciated that any other suitable type of dynamotor or an equivalent motor-generator set may be employed if desired and the customary functions of such a machine, for ex ample, driving air-compressors and furnishing energy for various auxiliary circuits may be utilized if deemed advisable.

The relay device RD is preferably of a familar solenoid type, and the actuating coil thereof is connected from the higher- 7 voltage terminal of the switch M1 to the and G2 are closed, the relay device receives therein,

' which lowervoltage terminal of the armature A l,

It will be observed that when the parallelconnecting switches M1 and M2, and G1 in a co-pending application of L. M. Perkins, Serial No. 83,721, filed March 13, 1916, has matured into. Pat. 1,268,052,

' gpanted May 28,- 1918, and assigned to the estinghouse Electric & Manufacturing Company. a The control device PK comprises a main drumportion MD that is provided with suitable stationary and movable contact members for gradually short-circuiting the field-circuit resistors .FRl and Flt-2 as the drum is moved through its successive positions andeiwhich corresponds to paral lel operation of'the momentum-driven machines and for again gradually short-circuiting the field circuit resistors as the driun is actuated through its successive positions 7 to which corresponds to' series connection of the regenerating machines. 7 An auxiliary interlocking drum ID is rotatable with the main drum MD, being preferably mounted on the same shaft 5, and .is employed for the purpose of controlling the operation ofthe mechanism OM, as described in connection with Fig. 2 whereby a step-by-step' movement of the PK controller is effected. The operating mechanism OM is of a familiar type and comprises a pinion 6 that is rigidly secured to the end of the shaft 5 'of the PK controller and meshes with a horizontally movable rack member 7 with the ends of which a plurality of pistons 8 and 9' are respectively associated. A plurality of suitable operating cylinders 10 and 11 are provided for the pistons 8 and 9 and a. plurality of valve members 12and 13 are adapted to admit fluid'p'ressure from any butare fully set forth and claimed illustrated position.

suitable source (not shown) through pipes or passages 14L and 15, respectively, in accordance with predetermined conditionsfto be described. The valve 12 is normally closed to exclude fluid-pressure from the cylinder 10 and to permit communication of the cylinder with the atmosphere. An actuating coil On is provided for controlling the action of the valve 12. On the other hand, the valve 13 is normally open to admit fluid-pressure to the cylinder 11, .whereby the operating mechanism is biased to the position shown, and an actuating coil Off is supplied for'closing the valve 13, as described in connection with Fig. 2.

To efiectforward movement of the controller PK, the onand off coils are simultaneously energized, whereupon the initial unbalanced fluid-pressure conditions are reversed to actuate the pistons toward the right. If it is desired to arrest the controller movement at anytime, the oil coil is de-" energized, and balanced-pressure conditions obtain in the two cylinders, thus positively and reliably stopping the controller. To efifect return movement, it is merely necessary to deenergize both coils, whereby the initial unbalanced-pressure conditions are restored, andthe pistons are moved to the 95. The auxiliary governing system that is shown in Fig.2 comprises, in addition to the actu'ating coils of the various switching devices that are illustrated in Fig. 1, a plu- V rality of interlocking contact members of a familiar type thatare illustrated in Fig. inconnection with the switch LS1, and the interlocking drum ID, a master controller MO that is adapted to occupya plurality of operative positions a to o when operated in one direction that corresponds to acceleration of the motors-and a plurality of operating positions a to is when moved in the opposite direction that corresponds to regeneration of the momentum-driven machines; a master reverser MR of a familiar type; a suitable source-of energy such as abattery B for energizing the various actuatin coils through the master controller 7 MO and through a plurality of train-line conductors TL, whereby multiple-unitoperation of my system maybe readily effected, as-will be understood; a control relay OR, for a purpose to be described; and certain auxiliary contact members of the change-over switch CO, the limit switch L and the relay device RD, which closes certain auxiliary circuits in a manner to be set forth.

Assuming that it is desired to efiect acceleratlon of the main .motors, the master controller MO may be actuated to its initial accelerating. position a, providedthat the master reverser'MR and the mainreversingswltch RS occupy their forward position-as illustrated, whereupon one circuitis established from the positive terminal of the battery B through conductor 20, train-line conductor 21, conductor 22, control fingers 23 and 24 which are bridged by contact segment 25 of the master controller in its position a, conductor 26, contact member 27 conductor 28 and contact member 29 or the master reverser MR in its forward position, conductor 30, train-line conductor 31, conductor 32, contact member 33 of the main reversing-switch BS in its forward position, conductors 34, 35 and 36, the actuating coil of the switch LS3, and also from conductor 36 through the parallel-related actuating coils of the switches LSl'and LS2 and an interlock Co-Acc., whence circuit is completed through conductors 37, 38 and 39, contact member 40 ofthe change-over switch CO in its position Acc., conductor 41, trainline conductor 42, conductor 43, control fingers 44 and 45 which are bridged by contact segment 46 of the master controller, conductor 47 train-line conductor 48 and conductor 49 to the negative terminal of the battery B. The switches LS1, LS2 and LS3 are thus closed as indicated in the sequence chart of Fig. 3.

Another circuit is simultaneously established from the contact segment 25 of the master controller through control finger 50, conductor 51, train-line conductor 52, conductor 53 and 54, interlock PK-a, conductor 55,, the parallel-related actuating coils of the field-circuit switches 1 and 3 and interlock LS3-in to the negative conductor 39.

A further circuit is established at this time from the contact segment 2501' the master controller through conductor 58, contact segment 59, conductor 60, contact segment 61 and control finger 62 of the various sections of the master controller; conductor 63, train-line conductor 63a, conductor 64, contact member 65 of the change-over switch CO in its position Acc., conductor 66, interlocks RR4-out and RR2out, conductor 67 the parallel-related actuating coils of the switches J1 and J2, conductor 68 and the interlock LS3-in to the negative conductor 39. Upon the closure of the switch J2, a holding circuit therefor is formed by interlock J2in which directly connects conductors 66 and 67 Still another circuit is established in position of the master controller from contact segment 25 through control finger 69, conductor 70, train-line conductor 71, conductor 72, interlocks J1-in and G1-out, conductors 73 and 74, the parallel-connected actuating coils of the switches R1 and BB1, conductor 75 and interlock LS3-in to the negative conductor 39. 7

Referring temporarily to the maincircuits that are shown in Fig. 1, the closure of the various switches that have been mentioned completes a main circuit from the trolley through conductor 76, the switches LS1, LS2 and LS3, conductors 77 and 78, one blade 79 of the cutout switch C12, conductor 80, the armatures A1 and A2, conductor 81, contact member 82 of the changeover switch CO in its position Ace, conductor 83 and certain contact members of the reversing-switch RS, field winding F 1, switch 1, field-winding F2, reversing switch RS, conductor 84, contact member 85 of the change-over switch CO, conductor 86, a second blade 87 of the cutout switch C12, conductor 88, switch R1, conductor 89, the entire resistor ARI, conductor 90, switches J1 and J2, resistor J R, conductor 91, the entire resistor A112, conductor 92, switch BB1, conductor 93, one blade 94 of the second motor-cutout switch C34 conductor 95, armatures A3 and A4, conductor 96, the actuating coil of the limit switch L, conductor 97, reversing switch RS, conductor 98, field winding F3, switch 3, field winding F4, conductor 99, reversing-switch RS, conductor 100, the second blade 101 of the cutout switch C34, conductors 102 and 103, contact member 104 of the change-over switch CO in its position Ace. and conductor 105 to the negative supply-circuit conductor Ground. (See Fig. 6.)

Referring again to Fig. 2, when the master controller MO is .actuated to its second accelerating position b a circuit is established from the positively energized contact segment 61, through control finger 106, conductor 107, train-line conductor 108, conductors 109 and 110, interlock J1in, conductor 111, the actuating coil of the switch J3, interlock 112-J3-out, conductor 113, interlocks M2-out, and LSl-in, conductor 115, contact member CO-Acc. and conductors 37 and 38 to the negative conductor 39. As soon as the switch J3 is closed, an additional holding circuit therefor is completed from the actuating coil thereof through interlock 112-J3-in and conductors 116 and 116cc to conductor 39, which additional circuit is employed in connection with certain other resistor-short-circuiting switches, as about to be described.

In position 0 of the master controller, the contact segment 25 engages control finger 117, whence circuit is completed through conductor 118, train-line conductor 119, conductors 120, and 121, the actuating coil of the switch B2, conductor 122, interlock 123-R2-out, conductor 124, interlock 125J3- in, and thence through conductor 113, as previously described. Upon the closure of the switch'R2, a holding circuit therefor is completed from conductor 122, through interlock 123-R2-in, and conductors 126 and 127 to the conductor 116.

in position (Z of the master controller, a circuit is completed from the contact segment 25 through control finger 128, conductor129, train-line conductor 130, conductors 131 and 132, the actuating coil of the switch BB2, conductor 133, and thence through interlock 123-B2-in, as already set forth. a

In position e,a circuit is completed from the contactsegment 25 through control finger 134, conductor 135, train-line conductor 136, conductors 137 and 138, the actuating coil of the switch B3, conductors 139 and 140, interlock 14l-R2-in, and thence through conductor 134, aspreviously described.

In position 7, a further circuit is completed from the contact segment 25 through control finger 142, conductor 143, train-line conductor 144, conductors 145 and 146, actuating coil of the-switch BB3, conductor 147 and interlock '148-B3in, a common holding circuit torthe switches B3 and BB3 being completed from the interlock 148 through conductor 127 to the conductor 116. In position 9, a circuit is established from the contact segment 61 of the master con-- troller through control finger 149, conductor 150, train-line conductor 151, conductor 152, contact member 153 of the change-over switch CO in its position Acc, conductors 154,155 and 156, the actuating coils of the switches B4 and BB4, conductor 157 and interlock LS3-in to the negative conductor. 39. In position 9, the initial energizing circuit of the actuating 601115 of the switches B1 and BB1 is also opened'at'ter the closure of the switchesrB-4 and BB4, by reason of the disengagement of the control finger 69 from the contact segment 25. 'Such action, however, does not vary the main-circuit resistance since direct shuntin paths around the main-circuit resistors A 1 and AB2 are provided through the switches B4 and BB4, respectively. An open main circuit at this time is prevented by the use of a holding circuit including conductors 35, 163, 208 and 209, interlocks B4-out and BBl -in and conductor 74 which is connected to the B1 and BB1 switch-actuating coils, thus preventing the opening of the switches B1 and BB1 until the closure of switches B4 and BB4, as more fully set forth below in connection with the switches 1 and 3, and 2 and 4.

In position it, a circuit. is established from the contact segment 25 through control fing'er 158, conductor 159,train-line conductor 160, conductors 161 and 162, the actuating; coils of the field-circuit switches 2 and 4 and conductor 38 to the negative conductor 39. The switches 2 and 4 are thus closed while the initial energizing circuit of the as-' sociated switches 1 and 3 is opened by reason of the disengagement of the control finger 50 from the contact segment 25 of the master controller, whereby the well-known normal-field connections are provided to effect a predetermined additional degree of by reason of a peculiar arrangement of in terlocking contact members, the switches 1 and 3 can not open until the switches 2'and 4 have closed, thus preventing an open main circuit, such interlocking connection including conductors 34 and 163, complementary interlocks 2-out and l-in, conductor 164 and conductor 55 which is connected to the actuating coils of the switches 1 and 3, thus insuring the energization of the actuating coils of these switches until the switch 2 has closed to interrupt the circuit between con ductor 163 and interlock l-in; V

The actuating coils of the switches 1 and 3 are thus provided withan initial energizing circuit directly from the master controller, as previously traced, a primary holding circuit including conductor 53, interlock l-in and conductors 164 and 55, and a-secondary holding circuit, as just recited, that is energized independently of the initial energizing circuit.

In position it, the switches B2, BB2, B3 and BB3 are also opened by reason of the disengagement of the contact segment 25 from the corresponding control fingers.

To efiect initial parallel connection of the motors, the master controller maybe moved toward its position 2', whereupon, at first, the contact segment 25 is disengaged from the control finger 158 and again engages control finger. 5O, thus effecting the closure of the switches 1 and 3 and the subsequent opening of switches 2 and 4 to again produce full-field conditions in the motors. A similar interlocking arrangement to that just'recited is also provided in this case and comprises conductor 35, complementary interlocks l-out and 2-in and conductor 162 which is connected to the actuating coils of the switches 2 and 4. Consequently, the en ergizing circuit for the actuating coils in question is maintained until such circuit is interrupted by the exclusion of the interlock 1-out when the switch 1 is closed.

Just before the master controller reaches its position a, the contact segment 61 engages control finger 166, whence circuit is completed through conductor 167, train-line conductor 168, conductor 169, contact memher 170 oi .the change-over switch CO in. its position Ace, conductor 171, interlocks 4'out,B1-out and BBQ-out, conductor 172,

the parallel-related actuating coils of the switches M1, M2, G1 and G2, conductor 17 3, switches 012 and '034 that are associated with the motor-cutout switches C12 and C34 in a familiar manner and interlock LS3-in to the negative conductor 39.

Immediately after the closure of the switches just mentioned, the contact segment 61 of the master controller becomes disengaged from the control fingers 62 and 106, thereby deenergizing the previously described cirouits of the actuating coils of the switches J1, J2 and J3, respectively. However, the opening of the switches J1 and J2 before the closure of the switches M1, etc. is prevented by an interlocking arrangement similar to that set forth in connection with the field-circuit switches, namely comprising conductors 36, 174 and 175, interlock Ml-out and interlock J2-in which is connected directly to the actuating coils of the switches J1 and J2. Thus, the energization of the J1 and J2 actuating coils is maintained through the holding circuit just recited until the switch M1 closes to interrupt the connection between conductor 17 5 and interlock J 2-in.

Moreover, in case the master controller is moved from a parallel position to the full series position It, to effect a speed reduction of the motors, a similar arrangement of interlocking, namely, conductors 36, 174 and 277, interlocks J2-out and Ml-in and conductor 172, prevents an open main circuit during such reversed bridging transition, which has not heretofore been accomplished, so far as I am aware.

Referring for the time being to Fig. 1, the main circuits that are established in the initial parallel connections of the motors that correspond to position i of the master controller may be set forth as follows: from the trolley through the main armatur es A1 and A main field windings F and F switch R4, and the resistor ARI, as previously described, conductor 182, switches G1 and G2, contact member 183 of the change-over switch CO in its position Ace, conductor 184- and conductor 103 to the negative supply circuit conductor Ground, as already traced. The circuit of the other motor is completed from the trolley through conductors 76, 77 and 185, switches M1 and M2, the resistor AR2, conductor 186, switch I i-R45, conductor 98 and thence through the other motors to ground, as previously described. The set of motors having the ar matures A1 and A2 and the resistor ARl thus comprises a circuit that is disposed in parallel relation to a circuit including resistor A112 and the motors having the armatures A3 and A4. (See Fig. 7.)

It should be noted that, by reason of the peculiar arrangement of resistor-short-circuiting switches that I have illustrated, the total number of switches for completing series-parallel operation of the motors is reduced over prior systems of the same general type that provide an equal number of resistance steps of control. In other words, the customary joining-switch, previously employed during transition, is omitted in my present system, all necessary circuit changes to complete transition being made by the resistor-varying switches, some of which thus serve a double function.

In position j (Fig. 2) the contact segment 25 re'e'ngages control finger 117 whence circuit'is established, as previously recited, through the actuating coil of the switch R2 and thence through the interlock 123-182- out, conductors 12 1 and 177, interlocks M2- in and LSl-in and thence through conductor 115 to the negative battery terminal, as previously described. Upon the closure of the switch R2, the hereinbefore-described holding. circuit for the actuating coil thereof is again completed.

In the next three positions 70, Z and m of the master controller, the control fingers 128, 13 1 and 1&2 respectively make contact with the contact segment 25 to effect the closure of switches BB2, R3 and BB3, as previously set forth.

In position n, the contact segment 61 of the master controller engages control finger 178, whence circuit is completed through conductor 17 9, train-line conductor 180, conductor 181, interlock Gl-in and conductors 73 and 7 1 to the actuating coils of the switches R1 and R-Rl in accordance with a circuit already traced. Although the resistor-short-circuiting switches are manipulated during the parallel operation of the motors in a different sequence from that employed during the series acceleration of the motors, it will be observed that the change of sequence is necessary by reason of the altered relations of the main-circuit resistors with respect to the motors, and, in either case, the manipulation of the switches is such as to gradually effect acceleration of the motors.

More specifically stated, the switches R1 and RRl are initially employed, whereby the current traverses the corresponding resistors in a certain direction during series acceleration; whereas the switches R4 and are employed during the first portion of parallel acceleration, and the current traverses the main resistors in the opposite direction. However, by connecting the intermediate switches, R2 and R3, for exam pie, from intermediate points of the resistor ARl to the terminal of the switch R1 that is remote from the armature A2, the same sequence of operation of the intermediate switches may be employed during both series and parallel operation, which is desirable for manufacturing and commercial reasons. The general arrangement of resistors and switches, whereby such reversal of current is effected and whereby the R1 and R4, and BB1 and RE L switches serve as additional series breaks in the main circuit, is of my present invention, while the specific connections just recited are set forth and claimed in the above identified c0pending application of L. M. Perkins. Moreover, the JR switch that has heretofore been employed during series acceleration of motors employing bridging transition, is omitted in my present system.

In the final position 0 of the master controller, the contact finger 158 again engages contact segment 25, while the control finger 50 again breaks contact with the segment 25. Consequently, the normal-field? connections are againeffected in a manner similar 'to'that accomplished at the end of the series change-over switch 00, contact member 201 of the change-over switch in its position Ace, conductor 202, train-line conductor 203, conductor 204, control fingers 205 and 45, which are bridged by contact segment 206 of the master controller in its position a and thence through conductor 47 to the negative battery terminal, as already described in connection with the motor acceleration. The change-over switch is thus actuated toits regenerative position. Reg, in a well-known manner.

Another circuit is. established from the positively-energized contact segment 59 of the master controller through the master reverser to conductor 36,-as hereinbefore described, and thence through the actuating coil of the switch LS3 and conductors 37 and 38 to the negative conductor 39. The switches LS1 and LS2 are not closed simultaneously with the switch LS3, by reason of the exclusion of the contact member QO-Acc. from the energizing circuits of their actuating coils. The closure of the switches LS1 and L -S2 is entirely dependent upon the upward actuation of the relay device RD, which takes place under suitable regenerative conditions, in a manner to be described.

,A further circuit is established from the conductor 34 through conductors 163,208, 209 and 210, control fingers 211and 212,

V which are bridged by contact segment 213 of the interlock drum ID, conductor 214,

contact member 215 of the change-over The actuating coils of the switches 1 and 3 are also initially energized by reason of the engagement of control finger 50 with contact segment 59 of the master controller in position a.

In the meantime, the field windings of: the main machines are exc ted by the generator armature G ln-accordancewlth c1rcuits about to be traced, and the'voltage of the main momentum-driven armatures is thus built up to point where the combined effect of the machine speed and field excitation suffices to produce a voltage across each of the two sets of armatures A1 and A2, A3 and A4, or, in other Words, impresses a voltage upon the actuating coil of the relay device RD, that is preferably higher than the supply-circuit voltage'by a'predetermined amount, whereupon the relay device is actuated to its upper position to complete the circuit of the actuating coils of the switches LS1 and LS2 from the conductor 36 through the actuating coils, conductor 225, switches 034 and 012 that are associated with the motor cutout switches C34Vand C12. auxiliary contact members 22 6 of the relay device B'D in its upper or closed position, and conductor 227 to the negatively-connected conductor 37. Upon; the closure of the switch LS2, a holding circuit therefor is formed from conductor 225, through conductor 228, interlock LS2-in, and conductor 229 to conductor 227, whereby the auxiliary contact members of the relay device RD are bridged,,and the device is inoperative with respect to varying the circuit connections during the remainder of the regenerative operation.

Upon the closureof thejswitch LS1, the.

from the conductor 154 through interlock J2-out and -M2-i'n and conductor 224. In this case, however, the conductor is opencircuited, and circuit is completed from interlock LS 1-in through contact members 114 of the limit switch L in its lower position and conductor 116a to the negative conductor 39. i

The progressive closure of the resistor short-circuiting switches just mentioned thus occurs a short-time after the closure of the switch LS1 to short-circuit the main re- ,sistors ARl and A112.

It should be observed that the actuating coils of the switches R2, R112, R3 and BB3 are energized in a predetermined sequence during acceleration in accordance with the configuration of the contact segment 25 of the master controller; whereas, during re- '223-CO-Reg, towhich energy is supplied generation, the actuating coils in question are energized from the contact member 223 of the change-over switch, but the desired sequence of operation is maintained by reason of the various interlocking contact members 123, 141, etc., as previously described.

Referring temporarily to the main circuits that are shown in Fig. 1, the connections. that are established by the actuation of the change-over switch CO and the closure of the switches just recited may be set forth as follows: One circuit is completed from the lower-voltage terminal of the armature A2, through conductor 81, contact member 187 of the change-over switch CO in its position Reg, conductor 86, blade 87 of the cutout switch O12, conductor 88, switch R1, conductors 89 and 182, switches G1 and G2, contact member 188 of the change-over switch, conductor 189, fieldregulating resistor FBI and conductors 190 and 191 to the negative supply-circuit conductor Ground. A similar circuit for the other set of motorsis completed from the lower-voltage terminal of the armature A4 through conductor 96, the actuating coil of the limit switch L, conductors 97 and 192, contact member 193 of the change-over switch, conductor 194, field-regulating resistor FR-2 and conductor 95 to the negative supply-circuit conductor Ground. The two sets of motor armatures are thus respectively connected in series relation with the regulating resistors FBI and FR2 across the supply circuit. (See Fig. 8.)

A further main circuit is established from the contact member 188 of the change-over switch through conductor 196, contact member 197, conductor 83, the complete field windings F1 and F2 and switch 1, conductor 84, contact member 198 of the changeover switch, conductors 184 and 103, contact member 104a of the change-over switch in its position Reg, conductor 199., the exciting armature G and conductor 199a to the conductor 190. A similar circuit for the other set of field windings is completed from the conductor 97 through conductor 98, the field windings F3 and F4 and switch 3, conductors 99 and 100 and thence to conductor 103 and the exciting armature G, as just described. The exciting armature G is thus connected to excite. the sets of main field windings through the resistors FRl and F32, respectively (see Fig. 8). However, such arrangement of main-circuit connections forms no material part of my present invention but is fully shown and described in a co-pending application of R. E. Hellmund, Serial No. 44,443, filed August 9, 1915, patented Apr. 1, 1919, No. 1298,706, and assigned to the Westinghouse Electric & Manufacturing Company.

It will be observed that the full-field switches 1 and 3 constitute the only means for opening the respective field-excitation circuits, during the regenerative period. Such opening means is necessary in order to prevent an excessive field-winding current at the end of the regenerative period when the machines tend to become motors again, and the switches 1 and 3 provide means for quickly opening the field-excitation circuits when the master controller is thrown to the 01f position. Heretofore, additional switches have been employed for the purpose in question, but my present invention permits the use of the same switches 1 and 3 that are employed during acceleration.

A further auxiliary circuit is then established from the conductor 208 through conductor 230, interlocks RR3-in, G2-in and (JO-Reg. and conductors 231 and 74 through the actuating coils of the switches R1 and BB1, as previously set forth.

lVhen the master controller is moved to its second regenerative position b, a circuit is completed from the contact segment 232, which is connected by conductor 23164 to the segment 61 of the master controller, through control finger 233, conductor 234, train-line conductor 235, conductor 236 where the circuit divides, one branch including conductor 237, control finger 238,

contact segment 239 and control finger 240 of the interlock drum ID, conductors 241 and 242, the actuating coil On and conductors 243 and 2436; to the negative conductor 39 and the other branch including conductor 244, control fingers 245 and 246 which are bridged by contact segment 247, conductor 248, interlocks G2in and 3-in, the actuating coil Off, interlock R3-in, conductor 249, auxiliary contact members 250 of the limit switch L in its lower or operative position and thence through conductor 243a to the negative conductor 39. By employing the interlock R3-in, the PK controller is prevented from operating, after the line switches LS1 and LS2 are closed, until predetermined portions of the maincircuit resistors Ali-1 and AR2 are shortcircuited. Inasmuch as the two actuating coils On and Off of the PK controller are simultaneously energized, forward movement of the controller to its position Z) occurs in accordance with the principles already set forth.

In position b of the interlock drum, the circuit of the actuating coil On is maintained by the engagement of the control finger 238 with the contact segment 239, while the control finger 245 becomes disengaged from the contact segment 247, thereby deenergizing the actuating coil Off and, consequently, efiecting the previously-de scribed balanced-pressure conditions in the operating mechanism OM to positively and reliably stop the PK controller in position .6".

In position of the master controller, the contact segment 232 engages control finger 166, whence circuit is completed through conductor 167, train-line conductor'168, conductor 169, contact segment 251 of the change-over switch, conductor 251a and control finger 252 which is connected to contact segment 247v of the interlock conductor 151, conductor 152, contact memher 253 of the change-over switch, conductor 253a and control finger 254 which engages contact segment 247 ofthe interlock drum in position 0" and thus permits movement of the drum, in the manner already de- I scribed, as far as position at;

In position 6 of the master controller, a control finger 255 engages the contact segment 232 whence circuit is completed through conductor 256, train-line conductor 257, conductor 258,0ontact member 259 of the change-over switch CO, conductor 260 and control finger 261 which engages the contact segment 247 of the interlock drum in position d and thus permits movement of the drum to position 6, which corresponds to the last parallel position of the regenerating armatures." 7

It will'be observed that one .of the stationary contact members of the limit switch L is connected through conductorw262, control fingers 263 and 264 which are intermittently bridged by a plurality of contact members 265;) and 265s'during a predetermined portion of the movement of the control drum from notch to notch, and conductor 266 to the other stationary contact member of the limit switch. It was found that when the limit switch was actuated to its upper or open position by reason of a predetermined increase of current, the controller PK at times tended to overshoot "the desired position and thus stick in a position intermediate the notches,thereby burning contact members, etc., or, in other words, the energization of the actuating coil Ofi was not niaintained for the exact length oftime necessary to insure the proper movement of the controller from one position to the next} Consequently, by short-circuiting the limit switch contact members between successive notches of the controller by the contact memcircuit of the actuating coil 1 position f.

bers 265p and 2658, such undesirable results are entirely obviated, and the controller moves forward positively and definitely fromnotch to notch.

However, it should be observed that the limit switch L may or may not beemployed, that is to say, the master controller maybe manipulated by the train'operator in such manner that the limit switch will not beactuated, but, under ordinary braking conditions, the limit switch is prefe'rably. employed, so that, when the machine current exceeds a predetermined value, the limit switch L lifts to temporaril interrupt the rest the movement of the controller PK. It will be understood that, when the limit switch is utilized, the master controller may be initially actuated to its 'posi-.

tions 6 or k, and the controller PK will then advance from notch to notch in accordance with the action of the limit switch L, as is familiar practice. When the vehicle is descending a grade, the manual manipulationof the master controller will permit ofthe variation of the'rate of speed; thus, the train operator may select the propernotch to provide a constant rate of speed on any grade, as will be appreciated.

If the'master controller MO ,is moved toward its initial series position f, a circuit is first established from. the contact segment 232 throughcontrol finger 267, vconductor 268, train-line conductor 269, conductors 270 and 271 and control finger 272 which engages the contact segment 239 of the interlock drum and, consequently, maintains the energization of the actuating coil On during the transitional movement of the controller PK. A new circuit for similarly maintaininghthe energization of the oil coil circuit comprisescontrol finger 296, which engages contact segment 232, conductor 297, trainline conductor 298, conductor 2 99 and con trol finger 300 which makes contact with segment 247 until just before position 7 of the interlock drum ID is reached. The control fingers 263 and 264 are also bridged by contact segment 273 between the positions 6 and 7" of the controller PK, thus bridging the stationary contact members of the limit switch L and serving to maintain the actuating coil 'Oflt' energized to insure the movement of the controller PK to its initial series As soon as the controller PK passes beyond its position 6, the contact segment 213 engages control finger 274, whence circuit is completed through conductor '27 5, contact member 276 of the change-over switch CO, where the circuit divides, one branch including conductor '66, interlocks RRl-in and RR-2-out, since the contact segment'232 disengages the corresponding control fingers ii and thus arof the master controller during the movement thereof to position 7, and thence through conductor 67 to the actuating coils of the switches J1 and J2, as previously set forth, and the other branch including conductor 278, interlock Gl-out as soon as the switch G1 has opened, as about to be set forth, and interlock J1-in and conductor 278a to the contact member 223-OO-Reg, thereby effecting the progressive closure of switches BB2, R2, R3 and BB3.

The switch J3 is also closed at this time by reason of the completion of a circuit from the interlock 223-CO-Reg. through conductors 219, 110, interlock J Lin and conductor 111 whence circuit is completed in accordance with circuits already traced. In addition, a circuit is completed from the positively energized conductor 163, through interlocks RR3-in, CO-Reg. and J l-in and conductor 156 through the actuating coils of the switches R4 and RRl as previously described.

The initial coil-energizing circuits of the switches M1, M2, G1 and G2 are also opened by reason of the disengagement of the contact segment 232, from the corresponding control finger 166 during the transitional movement of the master controller, although the opening of these switches is prevented until the switches J1 and J2 are closed by reason of an interlocking arrangement similar to that hereinbefore set forth in connection with the transition from series to parallel acceleration of the motors, such interlocking arrangement comprising the positively-energized conductor 174, conductor 277, interlocks J2-out and M1-in and conductor 172 to the actuating coils of the switches M1, M2, G1 and G2, thus insuring that the switches J1 and J2 shall be closed before the holding circuit just described for the switches M1, etc. is interrupted by the exclusion of the interlock J 2-out upon the closure of the switch J2. See Fig. 9 for the simplified main-circuit connections at this period.

It should be noted that the several M and G, and J switches that respectively correspond to parallel and series machine operation, are energized directly from the master controller during acceleration and through the interlock drum ID during regeneration. Such regenerative connection was found to be necessary to prevent false operation of the PK controller with respect to the governing step-by-step action of the master controller.

As soon as the master controller reaches its initial series position 7, one circuit is completed from the contact segment 232 through control finger 279, conductor 280, train-line conductor 281, conductor 282, actuating coil 283 of the control relay CR and conductor 284 to the negative conductor 39,

As soon as the interlock drum ID passes beyond its position e", a plurality of contact segments 285 and 286 that respectively correspond to contact segments 2&7 and 239 engage control fingers 290 and 293, whence one circuit is completed through conductor 291, cobperating contact members 292 of the control relay OR in its upper or closed position, interlocks G2-out and 3-in and thence through the off coil in accordance with a circuit that has hereinbetore been traced, while the other circuit is completed from control finger 293 through conductor 294, cooperating contact members 295 of the control relay conductor 242 and thence through the actuating coil On as previously set forth.

lVhen the controller PK occupies its position 7', the control finger 244 engages con tact segment 285 and the control fingers 272 and 240 still engage the contact segment 239.

The function of the interlock 32in that is connected in circuit with the oil actuating coil in conjunction with a control relay OR is to prevent the movement of the PK controller from afinal parallel, to the initial series position, that is, from c to f, until the corresponding main circuit transition of the machine is completed. On the other hand, it is deemed advisable to prevent return movement of the PK controller from a series position to a parallel position, and such movement is prevented by connecting segment 239 through conductor 271, interlock Gl-out and conductor 304: which is connected to the positively energized conductor 163. Thus an additional energizing circuit for the on coil is formed and cannot be broken until the master controller is returned to the oil? position, thereby precluding the undesirable return movement, in accordance with the operating principles of the mechanism OM.

Upon actuation of the master, controller to its position 9, the contact segment 232 engages control finger 233 whence the control finger 244 is energized to complete the circuit of the actuating coil Oil and thus permit movement of the controller PK to its position 9, wherein the control fingers 272 and 240 become disengaged from contact segment 239 and control fingers 238 and 293 engage contact segment 286 to maintain the energization of the on actuating coil.

Upon movement of the master controller through its positions h, z" and j, the control fingers 166, 1 19 and 255 are successively energized, thus completing the corresponding circuits to permit a corresponding step-bystep actuation of the controller PK.

In the final position of the master controller, the contact segment 232 engages control finger 62 whence circuit is completed through conductor 64 as hereinbefore described, contact member 301 of the changeover switch CO, conductor 302 and control finger 303 which engages contact segment 285 and thus effects the movement of the controller PK to its final position is".

It shouldbe noted that, by reason of the employment of sets of spaced segments 247 and 285, and 239 and 286, that are respectively connected in circuit with the off and the on actuating coils, either a forward or a backward step-by-step movement of the PK controller through either group of positions, a to e, or fto la, in accordance with the actuation of the master controller, is permitted, for the first time, so far as I am aware.

As previously mentioned, the foregoing description considers the case wherein the regenerative machines are operated at a relatively high speed so that initial parallel regenerative operation is permissible.

However, if the speed of the machines is sufficiently low to preclude ,the possibility of employing parallel-connected regenera tion, even though the controller PK is actuated to its final parallel position 6" to fullyexcite the main field windings, the further movement of the master controller MC will effect the energization of the control relay and, consequently, of the actuating coils On and Off and thus efiect a step-by-step movement of the controller PK until the voltage across the series-related main armatures preferably exceeds the supply-circuit voltage by a predetermined amount, whereupon the relay device will be actuated to its ug- 35 L 1 per position to close the line switches and LS2 in accordance with the previously traced circuits, and regeneration will take place from that point on to the final position of the controller PK. i V

I do not wish to be restricted to the specific circuit connections and arrangement and location of parts herein set forth, as

various modifications thereof may be effected without departing from the spirit and scope of my invention and I desire,

therefore, that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention: j V 1. The combination with a plurality of dynamo-electric machines adapted for seriesparallel operation, of a plurality of maincircuit multi-section resistors, a plurality of sets of switches for varying the active values of said resistors, and means for varying the order of operation of said switches during series and parallel motor operation, whereby transition of the motors to parallel 7 relation byemploying oneswitch from each 7 ries-parallel acceleration, and parallel-series parallel' operation, of a plurality of main- V circuit multi-section resistors, a plurality of sets of switches for varying the active values ing one more switch than there are corresponding resistor sections, means for connecting a first and a second switch from each set intermediate the corresponding ma- I chine and the respective terminals of the corresponding resistor,

, and means for initially employing the first and the second switch of each set during series and parallel machine operation, respectively. 7

3. The combination with a plurality of dynamo-electric machines adapted for series-parallel operation, of a plurality of main-circuit multi-section resistors, a pluralityof sets of switches for varying the active values of said resistors, means for connecting a first and a second switch from each set intermediate the corresponding machine and the respective terminals of the corresponding resistors, a switch for connecting the terminals of said resistors that are associated'with said second switches during series'operation of the machines, and means for effecting series-parallel transition of the machines by severally connecting the machines across the supply circuit while main taining said second switches closed and the other said switches open.

4. The combination with a plurality of dynamo-electric machines severally having armatures and subdivided field windings and adapted for both acceleration and regeneration, of a pair of switches for respectively effecting full-field and-normal-field connections of the machines, an auxiliary exciting armature, and means for connecting said exciting armature in circuit with said field windings and said full-field switch 7 during the regenerative period.

5. The combinatlon wlth a plurality of dynamo-electric machines severally having armatures and subdivided field windings and adapted for both acceleration and regeneration, of a pair of switches for respectively effecting full-field and normal-field connections of the machines during acceleration thereof, an auxiliary exciting armature,

a multi-position change-over switch for arranging the main-circuit connections-during both acceleration and regeneration, and

means for connecting said exciting armature in circuit with said field windings, certain contact members of said change-over switch and saic full-field switch, w'hereby the full-field switch constitutes the only means for opening the field-excitation circuit durin the re enerative eriod.

6. The combination with a plurality of dynamo-electric machines adapted for seregenerative operation, of a plurality of main-circuit multi-section resistors, an auxiliary main-circuit resistor means for initially employing all of said resistors during series acceleration of the machines, and

means for temporarilyemploying said auxiliary resistor during parallel-series transition of the regeneratlng machines.

7. The combination with a plurality of dynamo-electric machines adapted for series-parallel accelerating, and parallel-series regenerating operation, of a plurality of main-circuit multi-section resistors, an auxiliary main-circuit resistor, means for connecting said auxiliary resistor in circuit intermediate said entire multi-secti'on resistors to provide an accelerating step, and means for connecting the auxiliary resistor between predetermined portions of the multi-section resistors during regenerative transition of the main-armatures from parallel to series relation.

8. In a system of control, the combination with a dynamo-electric machine, and a pair of alternately-employed switches for respectively effecting difi'erent machine-circuit connections, of pairs of complementary interlocking means associated with the respective switches for preventing the opening of either switch before the closure of the other during the operation of the machine.

9. In a system of control, the combination with a dynamo-electric machine, and a pair of alternately-employed switches for respectively efi'ecting diflerent machine-circuit connections, of pairs of complementary electrical interlocks movable with the respective switches for preventingthe opening of either switch before the closure of the other during the operation of the machine.

10. In a system of control, the combination with a dynamo-electric machine, and a. pair of alternately-employed switches for respectively effecting such machine-circuit connections that the simultaneous opening of both switches would open-circuit the machine, of electrical interlocking means governed by the respective switches for insuring the closure of one switch prior to the opening of the other, whereby an open-circuit of the machine during operation thereof is prevented.

11, In a system of control, the combination with a dynamo-electric machine, and a pair of alternatelyemployed switches for respectively effecting such machine-circuit connections that the simultaneous opening of both switches would open-circuit the machine, of pairs of complementary electrical interlocking means for respectively opening and closing certain circuits in accordance with the opening and closing of each switch, and means for operatively connecting unlike interlocking means of the switches to prevent opening of one switch before 010- sure of the other.

12. In a system of control, the combination with a dynamo-electric machine, and a pair of alternately-employed switches for respectively efi'ecting such machine-circuit connections that the simultaneous opening of both switches would open-circuit the machine, of a plurality of actuating coils for said switches, pairs of complementary electrical interlocks movable with said switches and respectively corresponding to the open and closed conditions thereof, and means for connecting in series relation with the actuating coil of a closed switch the interlocks that respectively correspond to the closed position of that switch and the open position of the other switch, whereby said closed switch cannot open until the said other switch is closed.

13. In a system of control, the combination with a dynamo-electric machine, and a pair of alternately-employed switches for respectively effecting such machine-circuit connections that the simultaneous opening of both switches would open-circuit the machine, of a plurality of actuating coils for said switches, pairs of complementary electrical interlocks movable with said switches and respectively corresponding to the open and closed conditions thereof, a master controller for initially energizing the actuating coil of the first of said switches under predetermined conditions, means for connecting said actuating coil in series relation with the interlocks that respectively correspond to the closed position of the first switch and the open position or the second switch to a holding circuit that is energized independently of said initial energizing circuit, and means for interrupting said initial circuit and energizing the actuating coil of said second switch upon movement of the master controller to a predetermined position, whereby said holding circuit maintains the energization of said first actuating coil irrespective of said interruption until the interlock corresponding to the open position of said second switch interrupts the holding circuit upon the closure of said second switch.

14. In a system of control, the combination with a dynamo-electric machine, and a .pair of alternately-employed switches for respectively effecting such machine-circuit connections that the simultaneous opening of both switches would open-circuit the machine, of a plurality of actuating coils for said switches, pairs ofcomplementary' electrical interlocks movable with said switches and respectively corresponding to the open and closed conditions thereof, a master controller for energizing the actuating coil of the first of said switches under predetermined circuit conditions, and means for forming a primary holding circuit for said coil irrespective of said conditions through an interlock that corresponds to the closed position or said first switch, means for connecting said actuating coil in series relation with said last interlock and with the interlock that corresponds to the open position of the second switch to a secondary holding circuit that is energized independently of said initial energizing and holding circuit, and means for interrupting said initial circuit and energizing the actuating coil of said second switch upon movement of the master controller .to a predetermined position, whereby said secondary holding circuit maintains the energization of said first actuating coil irrespective of said interruption until the interlock corresponding to the open position of said second switch interrupts the secondary holding circuit upon the closure of said second switch.

15. In a system of control, the combination with a dynamo-electric machine having an armatureand a field winding and adapted for both accelerating and regenerative operation, of a plurality of machine controlling switches severally having actuating coils, a circuit including a variable resistor connected to said field winding during one kind of operation, a controller having contion with a dynamo-electric machine having an armature and a field winding and adapt- 1 ed for both accelerating and regenerative operation, of a plurality of machine-controlling switches severally having actuating coils, a circuit including a variable resistor connected to said field winding during regenerative operation, a controller having main contact members for varying said resistor, a plurality of governing coilsior said controller, a master controller for directly energizing all of saidactuating coils during the accelerating period and for energizing certain actuating coils and said governing andmeans for energizing the remaining aciary contact members on said resistor-controller. i

tion with a dynamo-electric machine, of a main controller forgoverning certain of the main-circuit connections, and a-master controller having electrical circuits connected with the main controller and further elec- V with the movements-of the master controller.

18. In a system of control, the combination with a dynamoclectric machine, of a controllenior governing certain of the maincircuit connections, a plurality of actuat-- and said main-circuit controller being-so:

related to said coils that forward and backward step-by-step movement of said maincircuit controller in accordance with the movements of said master controller is per- 19. In a system of control, the combination with a wdynamo-electric machine, of a controller for governing certain of the main-' circuit connections, a plurality or actuating coils adapted to effect forward movement of;

the controller when both coils are energized and backward movement when both coils are deenergized, and a master controller for energizing said actuating coilsthrough said main-circuit controller, 7 independent contact segments being provided on Saidmaincircuit controller for said coils and the configuration of the contact segments on said master controller and said main-circuit controller being such as to permit of-a forward;

or backward movement "of the main-circuit controller inacc'ordancewith the movements of the master controller. '7

20. In a system of control, the combination with a plurality of dynamo-electrim machines, of a plurality of sets of switches respectively corresponding to series and paralleloperation of the machines, a main-circuit controller having two groupsof positions corresponding to diiierent rangesofa operating speeds, electrically-controlled actuating means for said controller, and means associated with said: actuating means'and with certain of said switches for preventing movements of said controller: from one group of positions to the other prior to the completion of-the corresponding changes of main-circuit connections,

21. in a system of control, the combinachin'es adapted for parallel serics regenerative operation, of a plurality of sets of switches respectively"corresponding to, and a main-circuit controller having two spaced segments corresponding to, parallel and se-.

y-ries opera-tion, electrically-controlled actu- 17 In a system of control, the comb1na-- ating means for said; controller, and interlocking means associated with certain of said switches for governing said actuating means to prevent movement of said control? ler'from one group of positions to'the other prior to the completion of the corresponding transition of the machines.

22; In a system of control,-the combination with a'plurality of dynamo-electric machines adapted for parallel-series regenerative operation; of a plurality-of sets of switches respectively corresponding to, and

a main-circuit controller having two spaced segments corresponding to, parallel and?- tion with a plurality of dynamo-e1ectric.mail

coils directly during the regenerative period,

series operation, a plurality of actuating machine operation and respectively in circuit with the main-circuit controller segments corresponding to parallel and series operation, whereby the movement of said main-circuit controller from a position corresponding to the parallel segment to a position that corresponds to the series segment is prevented until the completion of the corresponding transition of the machines.

23. In a system of control, the combination with a plurality of dynamo-electric machines adapted for parallel-series regenerative operation, of a plurality of sets of switches respectively corresponding to, and a main circuit controller having two sets of spaced segments corresponding to, parallel and series operation, a plurality of actuating coils for said controller adapted to effect forward movement thereof when both coils are energized through the corresponding segments and backward movement when both coils are denergized, electrical interlocks respectively corresponding to the closed and the open positions of one of said switches that is employed during parallel machine operation and respectively in circuit with the main-circuit controller segments corresponding to parallel and series operation, a relay device having sets of contact members adapted to be respectively connected in circuit with the actuating coils and the series segments and having an actuating coil and a master controller embodying means for energizing the actuating coil of said relay device during series operation of said machines.

24. In a system of control, the combination with a supply-circuit and a dynamoelectric machine having an armature and a field winding and adapted for regeneration, of an auxiliary-field-excitation circuit including resistance means, a controller for varying the resistance thereof, actuating means for said controller, relay means for connecting the machine to said supply circuit under predetermined conditions, and means for rendering said actuating means operative only under additional predetermined conditions.

25. In a system of control, the combination with a supply circuit and a dynamoelectric machine having an armature and a field winding and adapted for regeneration, of an auxiliary field-excitation circuit, a controller for varying the resistance thereof, actuating means comprising a pair of coils to be simultaneously energized to effect a resistance-decreasing movement of the controller, a plurality of variable resistors in circuit with said armature, relay means for connecting the machine to said supply circuit under predetermined conditions, a plurality of switches for concurrently effecting the exclusion of said variable resistors from circuit, and interlocking means for preventing the energization of said actuating coils until a predetermined number of said switches have closed.

26. In a system of control, the combination with a plurality of dynamo-electric machines, of a plurality of sets of switches respectively corresponding to series and parallel operation of the machines, a maincircuit controller having two groups of positions corresponding to different ranges of operating speeds, electrically-controlled actuating means for said controller, and means associated with said actuating means and with certain of said switches for preventing a return movement of said controller from one group of positions to another under predetermined conditions.

27. In a system of control, the combination with a plurality of dynamo-electric machines adapted for parallel-series regenerative operation of a plurality of sets of switches respectively corresponding to, and a main-circuit controller having two spaced segments corresponding to, parallel and series operation, a plurality of actuating coils for said controller adapted to effect forward movement thereof when both coils are energizzed and backward movement when both coils are deenergized, a master controller for said switches and said main-circuit controller, an electrical interlock corresponding to the open position of one of said switches that is employed during parallel machine operation and included in circuit with the main-circuit controller segment corresponding to parallel operation and with one of said actuating coils to form a permanent energizing circuit therefor when the master controller and the main-circuit controller have been moved to their series positions, whereby return movement of the main-circuit controller to the parallel positions is prevented.

28. In a system of control, the combination with a supply circuit and a dynamoelectric machine adapted for acceleration and regeneration, of a plurality of maincircuit resistor sections, a plurality of switches for governing said resistor sections and severally having actuating coils, a master controller for energizing said coils in a predetermined sequence during acceleration, contact means for interconnecting one set of terminals of said coils and means for energizing said contact means under predetermined conditions during regeneration, and means for thereupon closing said switches in the same sequence as during acceleration. V

29. In a system of control, the combination with'a supply circuit and a dynamoelectric machine adapted for acceleration and regeneration, of a plurality of mainoircuit resistor sections,. a plurality of switches for governing said resistor sections and severally having actuating coils, a mas- 10 ten controllerfor energizing said coils in a predetermined sequence during acceleration, a change-over swltching devlce for arranglng var ous circult connectlons during both acceleration and regeneration and embodyar ssa ing contact means for interconnecting one set 15 of termlnals of said coils during regenera- 7 tion, an auxiliary field-excitation circuit, relay means for connecting the machine to the supply circuit under predetermined conditions, and interlocking means initially dependent upon said last connection for closing said switches in the same sequence as during acceleration. v r

In testimony whereof; I have hereunto subscribed my name this 29th day of Feb. 1916. V

ARTHUR J. HALL. 

